Three Australian soldiers were reportedly killed Wednesday by a rogue member of the Afghan army though details of the incident were still sketchy and remain under investigation, NATO said in a statement.

However, the Australian Defence Force (ADF) confirmed on Thursday morning that an incident in Oruzgan, where some 1550 Aussie Diggers were stationed, has been reported by the International Security Assistance Force (ISAF) command, in which NATO troops died from what appeared as a 'green-on-blue' assault.

The fresh insider attack was perpetrated by "an individual wearing an Afghan National Army (ANA) uniform," according to reports by Agence France Presse (AFP) quoting the official statement released by ISAF.

For its part, the ADF said in a statement that "Defence is currently in the process of informing the Next of Kin of the ADF personnel involved," effectively affirming the latest casualties absorbed by Aussie forces serving in Afghanistan.

NATO said spikes on such attacks, a number of which were attributed to Taliban infiltrators, have been recorded on 2012 that led to the killings of 34 ISAF-aligned soldiers, 26 of which were U.S. service members.

In the past few weeks alone, six American soldiers were shot at and killed by purported members of ANA, who NATO said were either insurgents guising as soldiers or legitimate local troops gone rogue.

Some of the killings, according to NATO officials, were found to have been caused by resentment, stress and personal dispute on the part of Afghan security forces.

NATO said security measures have been instituted due to such attacks, which include requiring all foreign troops to be on-guard while working with their Afghan counterparts.

NATO soldiers were also advised to lug along loaded weapons even when they are inside the premises of ISAF bases, according to Reuters.

Such security adjustments, however, plus the increasing insider attacks led to a high-level of distrusts between the Afghan Army and NATO soldiers, the latter now largely mentoring members of ANA in the run up to the scheduled foreign troops' withdrawal from Afghanistan on late 2014.

So far, 36 Diggers have died in the Afghan Mission, according to a Thursday report by NineMSN, seven of which were due to insider attacks.